Low-Energy Continuous X-Ray Spectrum in the 80 A to 180 A Region

Abstract

The paper deals with the relative intensity measurements of the soft x-ray continuous radiation from Mg, Al, Mn, Cu, Ge, and Ag targets bombarded by low-energy electrons. The investigations lie in the heretofore unexamined region from 80 to 180 A. Photometric measurements were carried out by the use of a previously calibrated grazing incidence spectrograph. In all cases the target layers were prepared by deposition in high vacuum. Accelerating potentials ranged from 600 to 3000 v. In addition to the study of the spectral shape of the bremsstrahlung, attempts were made to investigate the dependence of the intensity on takeoff angle. Various factors which might modify the source distribution are considered. For incident electrons in the above-mentioned range, the observed intensity at a wavelength $\lambda$ can be represented by a functional form such as $\frac{1}{{\lambda }^{\alpha }}$, where the parameter $\alpha$ is found to be in the range from 1.8 to 2.7. This parameter is related to the accelerating potential, the atomic number, and $\frac{\nu }{{\nu }_0}$, where $\nu$ is the radiated frequency and ${\nu }_0$ is the high-frequency limit. In the cases of Mg and Mn where the incident electron energies were of the order of 600 ev, comparison reveals that the observations are in agreement with numerical presentations of the Sommerfeld thin-target theory which assumes one radiating interaction between the incident electron and a single layer of target atoms.